1158 
the pressure increases, when the four-phases-tetrahedron turns its 
vapour-point away from the side (with the ternary terminating-points) 
and under constant P the temperature increases and at constant 
T the pressure decreases, when the four-phases-tetrahedron turns its 
vapour-point towards the side (with the ternary terminating-points). 
We now take en invarient (P or 7’) equilibrium, in which occur, 
besides a liquid LZ yet also the mixed-crystals M, M,...; we repre- 
sent this equilibrium by 
U ROL AIEN BONNEN 
and the occurring reaction by: 
UI CUM AEM NAE EN ens 
Of course one or more of the reaction-coefficients may be nega- 
tive. When all coefficients are positive, so that the liquid has a 
mediate composition, then (21) represents a congruent melting of the 
mixed-erystals; when one or more of the coefficients are negative, 
so that the liquid has a not-mediate composition then (21) represents 
a conversion of the one of mixed-crystals in the other, with forma- 
tion of liquid, consequently an incongruent melting. 
We shall call a mixture of the mixed-crystals M, M,... taken 
in such ratio, that it has the same composition as the liquid, the 
“reduced complex of mixed-crystals’”. Now we have: 
= (Aa) 2 — de, Ae, —1,8,—-..Sa—e . . (22) 
in which, therefore, c represents the concentration of the new sub- 
stance X in the reduced complex of mixed crystals; consequently 
c may be as well positive as negative. 
Therefore, we obtain again formula (11) in which AW is the 
heat, which is necessary for the congruent or incongruent melting, 
and AV the change in volume, occurring with this. We may assume 
again that in general AW is positive; AV may be, however, posi- 
tive or negative. 
When we only consider the change of the congruent or incon- 
gruent melting-point under constant pressure consequently, then 
follows the rule: 
when, on addition of a new substance, the concentration of that 
substance in the liquid (viz) is greater (smaller) than in the reduced 
complex of mixed crystals (viz c) than the (congruent or incongruent) 
melting-point of the mixed crystals under constant pressure decreases 
(increases). 
When the new substance, which is added, does not occur in the 
mixed-crystals, then, as #,a#,7,... are zero, also c=0. (11) then 
passes into: 
